As integrated circuit densities have scaled, the use of grating based patterning techniques and unidirectional design has become an integral part of pattern formation technology. Grating fabrication can be accomplished using a variety of techniques including directed self-assembly (DSA), sidewall image transfer, pitch split lithography, extreme ultraviolet lithography (EUV), electron beam lithography (EBL), and interference lithography.
The grating pattern is customized to form a circuit pattern. The ability to register customizing shapes to the grating pattern imposes a limitation on the spatial frequency (pitch) of the grating structure.
DSA is a technique for forming a sublithographic line/space pattern utilizing the phase separation of a block copolymer thin film. The composition of the copolymer controls both the resolution and the critical dimension (line width) of the pattern. A templating process controls both the orientation and ordering of the pattern. The templating process involves chemical epitaxy and/or graphoepitaxy. The advantages of DSA include a high resolution of features at dimensions less than 10 nm, compatibility with existing lithography techniques, and the ability for frequency multiplication and space subdivision.
A patterning technique of self-aligned patterning based on DSA graphoepitaxy using a tone inversion material, herein referred to as a tone inverted grapho-epitaxy method, is recently developed, in which a SiARC-like (Si anti-reflective coating) material is applied as the tone inversion material. An example of an SiARC-like material is JSR Corporation's JSR IRM-007. (Note: the term(s) “JSR” and/or “JSR-IRM” may be subject to trademark rights in various jurisdictions throughout the world and are used here only in reference to the products or services properly denominated by the marks to the extent that such trademark rights may exist.)